Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in PYTHON3):

Solution:
import queue

H, W = list(map(int, input().split()))
s = [list(input()) + ['#'] for i in range(H)] + [['#' for i in range(W+1)]]
white = sum([s[i].count('.') for i in range(H)])

q = queue.Queue()
s[0][0] = 1
q.put((0,0))

while not q.empty():
    i, j = q.get()
    for x, y in [(i+1,j), (i-1,j), (i,j+1), (i,j-1)]:
        if s[x][y] == '.':
            s[x][y] = s[i][j]+1
            q.put((x, y))

if s[H-1][W-1] in ['.', '#']:
    print(-1)
else:
    print(white-s[H-1][W-1])